Starting with sailor (3)
I believe the answer is:
tar
'sailor' is the definition.
(term for a sailor)
'starting with' is the wordplay.
'with' indicates the answer is hidden within the clue.
'TAR' is hidden in the letters of 'starting'.
(Other definitions for tar that I've seen before include "Sticky stuff for a kind of sailor" , "Black viscid substance" , "'Thick, dark, sticky liquid (3)'" , "Road-dressing for a sailor?" , "prepare for feathers?" .)